1. Field of the Invention
The present invention relates generally to coal deashing processes and, more particularly, but not by way of limitation, to improved separation techniques in coal deashing processes.
2. Description of the Prior Art
Various coal deashing processes have been developed in the past wherein coal has been treated with one or more solvents and processed to separate the resulting insoluble coal products from the soluble coal products.
U.S. Pat. Nos. 3,607,716 and 3,607,717, issued to Roach and assigned to the same assignee as the present invention, disclose processes wherein coal is contacted with a solvent and the resulting mixture then is separated into a heavy phase containing the insoluble coal products and a light phase containing the soluble coal products. In such processes, the light phase is withdrawn and passed to downstream fractionating vessels wherein the soluble coal products are separated into multiple fractions. Other processes for separating the soluble coal products from the insoluble coal products utilizing one or more solvents are disclosed in U.S. Pat. Nos. 3,607,718 and 3,642,608, both issued to Roach et al., and assigned to the same assignee as the present invention.